Sportsmetrics (a 6-week pre-season program varying in length from 60-120 minutes) and the Prevent Injury and Enhance Performance Program (PEP)[1] (a 20-minute warm up performed before every game and practice) not only significantly reduced injury risk but improved athletic performance.

The Sportsmetrics program
produced significant increases in lower extremity and abdominal
strength, vertical jump height, estimated maximal aerobic power, speed
and agility, while the PEP program significantly improved isokinetic
knee flexion strength but not vertical jump height, speed, or agility.

The other three programs studied (Myklebust, the "11," and Knee Ligament
Injury Prevention) did not improve both ACL injury rates and athletic
performance among female athletes.

The study by researchers at the Cincinnati Sportsmedicine Research and Education
Foundation in Cincinnati, Ohio, was published online in the journal Sports Health: A Multidisciplinary Approach.

Widespread use, increased compliance

Because the two programs had a positive influence on both injury reduction and athletic performance factors, lead author Frank R. Noyes, MD, expressed the hope that the findings might lead to greater compliance with training, and to intervention programs becoming widespread. Given the tremendous short- and long-term consequences[2] of ACL injuries, the fact that athletic performance indices also benefit might make "convincing athletes, parents, coaches, and others of the necessity for injury prevention training less challenging."

On the basis of a 16-year search of two databases, and including only peer-reviewed studies, researchers identified 5 ACL injury prevention programs that met selection criteria (ACL injury prevention programs for female athletes; athlete-exposure data; effect of training on ACL incidence rates for female athletes as determined by athlete-exposures, and assessment of athletic performance tests before and after participation in the ACL intervention program). All of the five included agility exercises, and all but the Myklebust included plyometrics[3].

The Sportsmetrics and PEP programs resulted in statistically significant decreases in ACL injury rates in high school female athletes participating in basketball and soccer. The PEP program approached statistical significance in reduction of the ACL injury rate of female college athletes.

Public health approach urged

It is well-known that adolescent and adult female athletes have a 4- to 8-fold higher increased incidence of sustaining a serious non-contact ACL injury compared with male athletes participating in the same sport or activity. But while a variety of ACL injury prevention programs have been developed over the past 15 years in an effort to decrease the risk of non-contact ACL injury among female athletes, program components, as well as the duration and intensity of training, vary widely.

Consensus on the ideal ACL injury prevention program remains elusive, largely "because of the complex, multi-faceted problem of the injury itself," although a recent meta-analysis of published ACL injury prevention programs suggests that plyometric[3] and strengthening components are more important than balance training, and that the favorable effects of training are most pronounced in female soccer players under18 years of age.[2]

Compliance rates with training also vary widely, although the reasons for the discrepancies are still unclear. While "some maintain that ACL intervention programs that involve 60 to 120 minutes of training for 3 days a week are difficult to conduct," Noyes noted that the "most effective program in [our] review in regard to athletic performance enhancement was Sportsmetrics, which requires this amount of time."

The development of the ideal ACL prevention program will require development of an "understanding of the multiple factors that influence the successful implementation of these programs," Noyes said.

Unanswered questions

Left unanswered by the current study were whether "newer sports-specific programs were also effective in significantly reducing thge incidence of ACL injuries" and "if the improvement in fitness and functional indices as a result of ACL injury prevention training translates into enhanced player performance during competition." Future studies are needed, Noyes concluded, on "programs shorter in duration [to] consider the intervention before the start of the athletic season so that the effect of training alone on athletic performance may be measured."